Quantum Mechanics and Atomic Theory Chapter 12 E-mail: benzene4president@gmail.com Web-site: http://clas.sa.ucsb.edu/staff/terri/

Quantum – ch 12 1. A green photon has a frequency (v) of 5.45 x 108 MHz a. Calculate the photons wavelength (λ) in nm b. Calculate the energy (in J) of one photon and for one mole of photons (kJ/mol)

Quantum – ch 12 2. Determine the following: a. Higher frequency: IR or UV b. Higher Energy: X-Rays or Microwaves c. Longer wavelength: yellow or purple

Quantum – ch 12 3. According to Heisenberg uncertainty principle; a. the momentum of a particle cannot be measured precisely b. neither the position nor the momentum can be measured precisely c. the position and the momentum of a particle can be measured precisely, but not at the same time d. the positon of a particle cannot be measured precisely

Quantum – ch 12 4. From the following list of observations, choose the one that most clearly supports the conclusion that electrons have wave properties. a. the emission spectrum of hydrogen b. the photoelectric effect c. the scattering of alpha particles by metal foil d. diffraction e. cathode "rays"

Quantum – ch 12 5. Calculate the wavelength of a beryllium atom traveling at 15% the speed of light.

Quantum – ch 12 6. It takes 208.4 kJ of energy to remove 1 mol of electrons from the atoms on the surface of rubidium metal. If rubidium metal is irradiated with 254-nm light, what is the maximum kinetic energy (kJ/mol) the released electrons can have?

Quantum – ch 12 7. Consider the following transitions. Which will emit light with a longer wavelength? a. n = 4  n = 2 or n = 3  n = 2 b. n = 3  n = 1 or n = 1  n = 3 c. n = 5  n = 3 or n = 3  n = 1

Quantum – ch 12 8. Calculate the wavelengths (nm) emitted for the following electronic transitions in a hydrogen atom. a. n = 5  n = 3 b. n = 3  n = 1 c. How would your answers vary if the electronic transitions were for Ne9+?

Quantum – ch 12 9. An excited hydrogen atom with an electron in n = 5 state emits light having a frequency of 6.9 x 1014 s-1. Determine the principal quantum level (n) for the final state in this electronic transition.

Quantum – ch 12 10. The figure below represents part of the emission spectrum for a one-electron ion in the gas phase. All of the lines result from electronic transitions from excited states to the n = 3 state. Wavelength A B C a. What electronic transitions correspond to lines A and B? If the wavelength of line B is 142.5 nm, calculate the wavelength of line A.

Quantum – ch 12 11. An electron is excited from the ground state to the n = 3 state in a hydrogen atom. Which of the following statements is/are true? a. It takes more energy to ionize the electron from n= 3 than from the ground state. b. The electron is farther from the nucleus on average in the n = 3 state than in the ground state c. The wavelength of light emitted if the electron drops from n = 3 to n = 2 is shorter than the wavelength of light emitted if the electron falls from n = 3 to n = 1. d. The wavelength of light emitted when the electron returns to the ground state from n = 3 is the same as the wavelength absorbed to go from n = 1 to n = 3. e. The ground state ionization energy of He+ is four times the ground state ionization of H.

Quantum – ch 12 12. Calculate the ground state ionization energy (in kJ/mol) and the wavelength (in nm) required for B4+.

Quantum – ch 12 13. How many electrons in any one atom can have the following quantum numbers? a. n = 5 b. n = 6, l = 0 c. n = 4, l = 2 d. n = 4, l = 3, ml = -2 e. n = 2, l = 0, ml = 0, ms = -1/2

Quantum – ch 12 Quantum Numbers 1. n ⇒ principal quantum number ⇒ proportional to the size and energy of the orbital ⇒ range is 1 to ∞ 2. l ⇒ angular momentum quantum number ⇒ shape of the subshell ⇒ range is 0 to ∞ 3. ml ⇒ magnetic quantum number ⇒ orbital orientation ⇒ range is –l to +l 4. ms ⇒ electron spin quantum number ⇒ +1/2 or -1/2

Quantum – ch 12

Quantum – ch 12 l=0 ⇒ s l=1 ⇒ p l=2 ⇒ d l=3 ⇒ f

Quantum – ch 12 Cl Ni 14. Fill in the following table: Cr Ag Te2– Fe2+ Element Ground State Electron Configuration Number of Valence Electrons Number of Unpaired Electrons Cl Ni Cr Ag Te2– Fe2+

Quantum – ch 12 Aufbau principle ⇒ electrons will fill from low to high energy Hund’s Rule ⇒ When filling degenerate orbitals don’t pair up until each orbital has 1 e–

Quantum – ch 12 Electron Configuration ⇒ Order of filling is left to right and top to bottom on the periodic table

Quantum – ch 12 15. Determine if each of the following corresponds with an excited state or ground state electron configuration. a. [Ar]4s24p5 b. [Kr]6s1 c. [Ne]3s23p4

Quantum – ch 12 16. Which of the following has the largest radius? a. Al or Si b. F or Cl c. K+ or S2- d. Ar or K+

Quantum – ch 12 17. Which of the following has the greatest ionization energy? a. K or Ca b. P or As c. Sr or Sr2+

Quantum – ch 12 18. The successive ionization energies for an unknown element are: I1 = 896 kJ/mol I2 = 1752 kJ/mol I3 = 14,807 kJ/mol I4 = 17,948 kJ/mol Which family does the unknown element most likely belong?

Quantum – ch 12 19. Which of the following has the most negative electron affinity? a. Br or Kr b. C or Si